The best solution is to upgrade Redmine to the latest version. But if you really want to use Redmine 0.6.0 on a box running Rails 2.0, please freeze your Rails version for Redmine (it won't affect your other Rails applications) by typing this command from your Redmine directory:

If you want the commits to be retrieved periodically by Redmine in the background for all your repositories, uncheck 'Autofetch commits' setting and add a cron that runs (with appropriate environment):